page_title: Coast Range Arc
section_title: Geological importance
hierarchical_section_title: Coast Range Arc / Geology / Geological importance
caption_attribution_description: English: Plate distribution 55 million years ago. Arrows represent direction of subduction along North America.
context_page_description: The Coast Range Arc was a large volcanic arc system, extending from northern Washington through British Columbia and the Alaska Panhandle to southwestern Yukon. The Coast Range Arc lies along the western margin of the North American Plate in the Pacific Northwest of western North America. Although taking its name from the Coast Mountains, this term is a geologic grouping rather than a geographic one, and the Coast Range Arc extended south into the High Cascades of the Cascade Range, past the Fraser River which is the northward limit of the Cascade Range proper.
  The Coast Range Arc formed as a result of subduction of the Kula and pre-existing Farallon Plates. It is most famous for being the largest granitic outcropping in North America, which then it is usually referred to as the Coast Plutonic Complex or the Coast Mountains Batholith. It is a coast-parallel continental volcanic arc similar to the Andes of South America and the largest continental volcanic arc fossil in the world.
context_section_description: Intrusions of the Coast Range Arc are intruded by widespread basaltic dikes. These dikes, although not voluminous, provide an important sampling of the post-arc lithosphere. Additionally, widespread volcanic belts, such as the Anahim Volcanic Belt, lie in the middle of the Coast Range Arc. Volcanics that form the Anahim Volcanic Belt are not strictly related to Coast Range Arc subduction, but might have formed as a result of the North American Plate sliding over a place that has experienced active volcanism for a long period of time which is described as the Anahim hotspot. During its formation, it lay beneath granitic intrusions of the Coast Range Arc. The approximately 20-kilometre (12 mi) long Bella Bella and approximately 6-kilometre (4 mi) long Gale Passage dike swarms lie in granitic intrusions of the Coast Range Arc and are used to calculate the first appearance of the Anahim hotspot about 13 and 12 million years ago.
caption: Plate distribution 55 million years ago. Arrows represent direction of subduction along North America.
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